Method of preparing coffee extract



Jan. 29, 1935. o. P. c. BREDT 1,989,077

METHOD OF PREPARING COFFEE EXTRACT Filed Jan. 14, 1950 2 Sheets-Sheet l 1935i 0. P. c. BREDT METHOD OF PREPARING COFFEE EXTRACT 4 2 Sheets-Sheet 2 Filed Jan. 14, 1930 iyfz.

Patented Jan. 29, 1935 I 1,989,077

UNITED STATES PATENT OFFICE 1,989,077 METHOD OF PREPARING COFFEE EXTRACT Otto Paul Curt Bredt, New York, N: Y., assignor to Straitway Cofl'ee, Incorporated, Keyport, N. J a corporation of Delaware Application January 14, 1930, Serial No. 420,678

2 Claims. (01. 99-11) This invention relates to a novel and improved by preserving the aroma and other valuable inmethod of preparing a highly concentrated coiiee gradients and increasing the yield.

extract which may be reduced to a dry or pow- In the accompanying drawings, in which I have dered form. The dry or powdered product is illustrated certain apparatus which may be used A readily soluble in water. to advantage in the practice of the invention; 6

According to prior art practices, in making a Fig. 1 is a diagrammatic floor plan showing an coil'ee extract, it has been the custom to percolate arrangement of apparatus by means of which the the ground coiIee bean with hot or' cold solumethod may be practiced. tions either in one stage or'in successive stages. Fig. 2 is a vertical section through an improved 1" Thismethod requires water or other liquid having vacuum drum dryer which also may be used to about 1 times the weight of the coifee, a large advantage. amount of which must later be evaporated, and Referring now to Fig. i, I have shown therein requires a considerable length of time. If done an apparatus for pracicing a series of steps, rapidly the yield is decreased because the valueachstep consisting in the saturation of a batch I able ingredients of the cofl'ee are not extracted of coffee beans and the subjection of the satul5 from'the bean, and ii a longer time is taken, in rated batch to a high pressure. The details of order to extract these ingredients, then valuable the apparatus may vary quite widely, without ingredients are lost due to escape of the aroma, affecting the invention, and therefore I have the'aroma carrying with it may of the most valu' merely indicated the location of the various able oi the ingredients. parts of the apparatus. At 1, 2 and 3, are shown 20 It the percolation is done with hot water, more mixers, in which coflee beans may be saturated,

oi the aroma escapes. and after saturation the batches are moved re- The solution obtained by percolation is a liquid spectively to the presses 4, 5 and 6, this movecontaining a large amount of water with respect ment of the batches being indicated by the 5 to the amount oi. coffee, and this must be conarrows 7.

centrated before sale. The amount of concentra- Connected to each press is a tank, these tanks tion already present depends upon the number being designated 8, 9 and 10, respectively. The of successive percolations to which the coffee has liquor from each press may be forced into the been subjected. I! the concentration is high, the respective tank by means of pumps 11, one of solution is put into a dryer such as a vacuum which is located in each line between a press and 3 drum dryer and reduced to powder form, whereas tank. In the line between the press 4 and the it the concentration is low, the concentration tank Bis a filter 12. There is also provided a conmust be increased by a preliminary evaporation nection 13 from the tank 9 to the mixer 1, and a I before being put into the dryer, to bring the connection 14 from the tank 10 to the mixer 2, product within the range of consistency which the these connections being provided with valves 15 $5 dryer can operate. and 16. The arrows 1'7 and 18 indicate movement 11' the same batch of coffee has been subjected of cakes from presses 4 and 5 to the mixers 2 to successive percolations, the yield is relatively and 3, respectively, as will be more fully d high, and if successive batches of coffee have been scribed presently. subjected to percolation with the same liquid, 9. When the apparatus is first started, the first h concentration n yi i ned, but bestep is to saturate ground coflfee beans with water cause of the time consumed, a large amount of in the mixer 1, the water being supplied at 19. the aroma has escaped. On the other hand, in The ratio of coffee to water is about 1:1 this the second instance, where there has been only a being abgut', th proportion necessary to saturate, Small um 0! p fi't ons, and where the the beans. The saturated coffee is then conveyed product has to be subjected to evaporation before to the press 4, as indicated by the arrow '7, and en e th d ye the yield is small, and here subjected to a high pressure of about 500 lbs. per $00 $18186 D the aroma ill e t. in th square inch. This will largely separate the disi s aroma being lost n large de ee in solved parts of the coffee beans, together with the go the preliminary evaporation before entering the oily substances from the remaining fibre. This dryer. remaining fibre I then convey to the mixer 2, this According to my invention, I preserve the aroma movement being indicated by the arrow 17, and in both by decreasing the time taken in the treatthis mixer the fibre or cake is saturated again, to ment, and by increasing the concentration, therethis time with hot water supplied at 20 with about I solids, such as the same proportions by weight of coffee and water as in the first mixture.

After saturation, the cake is conveyed to the press 5, and again subjected to high pressure, the liquor being pumped from the press to the tank 9. This liquor may be conveyed through the connection 13 to the mixer 1 and there used to saturate a fresh batch. The cake from the press is conveyed as indicated by the arrow 18, to the mixer 3, where it'is again saturated, this time preferably with boiling water supplied at 21, the proportions by weight of coffee and water being substantially the same as before. After saturation, the batch from the mixer 3 is conveyed to the press 6, and again subjected to high pressure. The liquor from this pressing is pumped to the tank and may be used in the mixer 2.

The above describes the first operation when the apparatus is started. It is obvious, however, that the apparatus is intended for continuous operation over long periods. In continuous operation, the process may be described as follows:

A fresh bath of coffee beans, preferably ground, is supplied to the mixer 1, where his mixed with liquor supplied from the tank 9. The batch is then conveyed to the press 4 for extraction of the liquid therefrom, and then the cake is conveyed to the mixer 2 for saturation with liquor from the tank 10. The saturated cake is then treated in the press 5 and conveyed to the mixer 3 for saturation with fresh boiling water. In other words, the process first described is continuously repeated, except that the liquid used for saturation of the coffee in mixers 1 and 2 is liquor extracted from previously treated batches.

The result is that a batch of coffee beans is sub- 7 jected to successive saturations with the same liquid. the last saturation being with fresh water and the first saturation being with liquor extracted from preceding batches. The operation on the fresh batch of beans at the first pressing in the press 4, serves to extract the major part of the soluble matter, and the second pressing extracts the major part of the remaining soluble the coffeo-tannic acid compounds, caffeines, or in other words the substances which may be called the] bitter ingredients. The last pressing with boiling water at 100 C. extracts the remaining ingredients and insures a high yield but is not always necessary.

The extract which has been passed from the press 4 through the filter 12 to the tank 8 is now highly concentrated and is ready for drying, and the drying should be performed at once. While I prefer to dry the extract, it is; of course, to be understood that if desired the extract may be used in its liquid form. The concentrate at this time contains between 15 and 40% of the solids which contain the valuable ingredients of the coffee, particularly the ingredients making the aroma. In order to avoid the loss of aroma and other valuable ingredients, the concentrate is conducted directly from the tank 8 through the pipe 22 to the dryer, which may be a vacuum dryer of any well-known type, although preferably I prefer the form of dryer shown in Fig. 2.

In Fig. 2, I have shown a chamber 19 connected at 20 to an exhaust for forming a vacuum in the chamber, and connected at 21 to the receptacle 22. Within the dryer is a revolving drum 23, preferably'made of highly polished bronze, revolving on a horizontal axis in the direction indicated by the arrow 24. Disposed in the top of the chamber is a spray 25 designed to spray the liquid coffee extract on to the top of the drum,

preferably at one side of the vertical plane passing through the horizontal axis of the drum. It will be seen that the drum rotates in a direction such that the top of the drum is moving from this plane toward the spray, so that the sprayed .material has practically no chance of working down to the right of the drum, as viewed in Fig.

2, but will be carried by the drum in a counterclockwise direction. The extract will be dried to a powder during movement of the drum, and will be scraped therefrom as by a knife 26, and may be received on an apron 27 which will guide it into the receptacle 22.

By my invention, I materially shorten the time during which the coffee remains in "solution. This is important, because while in solution the coffee loses its flavor very quickly. -At the same time, I obtain a high yield while retaining the aroma and other valuable ingredients of the coffee beans. I

, I claim:

1. The method of making a product containing the valuable ingredients of coffee, which comprises performing a series of three successive steps on a batch of coffee beans to obtain a liquid extract, each step consisting in saturating said batch with a liquid and subjecting the batch totract out of said first-named batch, saturatingthe pressed solids of said first-named batch with hot aqueous liquor, again pressing said firstnamed batch and using the extract therefrom to extract a fresh batch of roasted coffee and so on repeatedly.

- OTTO PAUL CURT BREDT. 

